Adjustable desk lamp



FIG. 1 is a front elevational view of an adjustable desk lamp showing my new design;

FIG. 2 is a right side elevational view thereof, the left side being a mirror image;

FIG. 3 is a rear elevational view thereof;

FIG. 4 is a top plan view thereof;

FIG. 5 is a bottom plan view thereof; and,

FIG. 6 is a front, right side perspective view thereof. 

The ornamental design for a adjustable desk lamp, as shown and described. 